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A primary role of developmental instability in sexual selection
Michal Polak1, Phillip W Taylor
1Department of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221-0006, USA. polakm@email.uc.edu
Proceedings. Biological Sciences
|October 18, 2007
Summary
Fluctuating asymmetry (FA) and minor morphological abnormalities (MMAs) are linked indicators of developmental instability (DI). In Drosophila, selection favors reduced DI in courtship ornaments, suggesting DI can drive adaptive evolution.
Area of Science:
- Evolutionary biology
- Developmental genetics
- Sexual selection
Background:
- Fluctuating asymmetry (FA) is a proposed indicator of developmental instability (DI).
- DI is also assessed via minor morphological abnormalities (MMAs) in clinical genetics.
- The adaptive and genetic bases of FA and its link to DI are debated.
Purpose of the Study:
- To integrate FA and MMAs as DI measures in sexual selection and quantitative genetics.
- To investigate the evolutionary and genetic underpinnings of DI in a natural population.
- To examine the role of DI in adaptive evolution of sexual traits.
Main Methods:
- Multivariate analyses of FA and MMAs in Drosophila bipectinata sex combs.
- Quantitative genetic study of a natural population.
- Selection analyses on sexual ornaments.
Main Results:
- FA and MMAs are positively correlated, reflecting a shared buffering system.
- Selection favors reduced FA and MMAs in the male Drosophila sex comb.
- Ornament size is positively correlated with DI (FA and MMAs), contradicting negative size-DI scaling expectations.
- Significant additive genetic variance for MMAs indicates evolutionary potential.
- Elevated DI in New Caledonian populations suggests it facilitates adaptive evolution.
Conclusions:
- FA and MMAs are reliable, complementary DI indicators.
- Selection actively reduces DI in a condition-dependent sexual ornament.
- DI is not solely a marker of genetic quality; it can be a target for adaptive evolution.
- Elevated DI may capacitate adaptive evolution in natural populations.
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